Improve meson build.

-Add all required packages as wrap dependencies
-Move source lsitnings to separate files
-Proper dependencies declarations
-Set global D compiler arguments
-Add few asserts
-Add test exe
-Other small improvements

Tested with dmd with betterC, demos executable has to be run from 'demos' directory to properly load assets.

demos/meson.build

@@ -1,45 +1,35 @@
-demos_src = [
-	'source/app.d',
-	'source/demos/brick_breaker.d',
-	'source/demos/snake.d',
-	'source/demos/simple.d',
-	'source/demos/sandbox.d',
-	'source/demos/bullet_madnes.d',
-	'source/demos/particles.d',
-	'source/demos/physics.d',
-	'source/demos/space_invaders.d',
-	'source/game_core/basic.d',
-	'source/game_core/job_updater.d',
-	'source/game_core/rendering.d',
-	'source/game_core/collision.d',
-	'source/gui/component.d',
-	'source/gui/manager.d',
-	'source/gui/template_.d',
-	'source/gui/tool_circle.d',
-	'source/gui/system.d'
-]
+# Files
+demos_src = files()
+external_src = files()
+subdir('source')
+subdir('external')
 
-external_src = [
-	'external/sources/mmutils/thread_pool.d',
-	'external/sources/glad/gl/gl.d',
-	'external/sources/glad/gl/loader.d',
-	'external/sources/glad/gl/ext.d',
-	'external/sources/glad/gl/all.d',
-	'external/sources/glad/gl/funcs.d',
-	'external/sources/glad/gl/gles2.d',
-	'external/sources/glad/gl/enums.d',
-	'external/sources/glad/gl/types.d',
-	'external/sources/cimgui/cimgui.d'
-]
+demos_inc = include_directories('source/')
+external_inc = include_directories('external/sources/')
 
-demos_inc = include_directories(['source/'])
+# Argumesnts
+versions = ['BindSDL_Image','SDL_208', 'BindBC_Static', 'BindSDL_Static']
 
-#link_args += '-rpath=libs/linux/x64/'
-link_args += '-L=' + meson.current_source_dir() + '/libs/linux/x64/libcimgui.so'
-link_args += '-L' + meson.current_source_dir() + '/libs/linux/x64'
-link_args += '-lcimgui'
-#,"SDL2_image
+# Dependencies
+bindbc_loader_dep = dependency('bindbc-loader')
+bindbc_sdl_dep = dependency('bindbc-sdl')
+cimgui_dep = dependency('cimgui')
+sdl2_dep = dependency('SDL2')
+sdl2_image_dep = dependency('SDL2_image')
 
-executable('demos', [demos_src, external_src], include_directories : [demos_inc, utils_inc, inc], d_args: args, link_args: link_args, 
-    d_module_versions: ['BindSDL_Image','SDL_2010'], link_with: [ecs_lib, ecs_utils_lib], dependencies: [bc_loader_dep,sdl_dep],
-	build_rpath: '-L' + meson.current_source_dir() + '/libs/linux/x64/', install_rpath: 'libs/linux/x64/')
+subdir('utils') # Utils library
+
+executable('decs-demos', [demos_src, external_src], 
+	include_directories : [demos_inc, external_inc],
+	d_module_versions : versions,
+	link_with : [ecs_lib, ecs_utils_lib],
+	dependencies : [
+		bindbc_loader_dep,
+		bindbc_sdl_dep,
+		cimgui_dep,
+		decs_dep,
+		ecs_utils_dep,
+		sdl2_dep,
+		sdl2_image_dep,
+	],
+)